Glycemic variability and glucose complexity in critically ill patients: a retrospective analysis of continuous glucose monitoring data

Abstract

IntroductionGlycemic variability as a marker of endogenous and exogenous factors, and glucose complexity as a marker of endogenous glucose regulation are independent predictors of mortality in critically ill patients. We evaluated the impact of real time continuous glucose monitoring (CGM) on glycemic variability in critically ill patients on intensive insulin therapy (IIT), and investigated glucose complexity - calculated using detrended fluctuation analysis (DFA) - in ICU survivors and non-survivors.MethodsRetrospective analysis were conducted of two prospective, randomized, controlled trials in which 174 critically ill patients either received IIT according to a real-time CGM system (n = 63) or according to an algorithm (n = 111) guided by selective arterial blood glucose measurements with simultaneously blinded CGM for 72 hours. Standard deviation, glucose lability index and mean daily delta glucose as markers of glycemic variability, as well as glucose complexity and mean glucose were calculated.ResultsGlycemic variability measures were comparable between the real time CGM group (n = 63) and the controls (n = 111). Glucose complexity was significantly lower (higher DFA) in ICU non-survivors (n = 36) compared to survivors (n = 138) (DFA: 1.61 (1.46 to 1.68) versus 1.52 (1.44 to 1.58); P = 0.003). Diabetes mellitus was significantly associated with a loss of complexity (diabetic (n = 33) versus non-diabetic patients (n = 141) (DFA: 1.58 (1.48 to 1.65) versus 1.53 (1.44 to 1.59); P = 0.01).ConclusionsIIT guided by real time CGM did not result in significantly reduced glycemic variability. Loss of glucose complexity was significantly associated with mortality and with the presence of diabetes mellitus.

Complexity of Continuous Glucose Monitoring Data in Critically Ill Patients: Continuous Glucose Monitoring Devices, Sensor Locations, and Detrended Fluctuation Analysis Methods

“…The two previous studies of DFA in ICU patients only used monofractal DFA to assess glucose complexity, 22,23 but this study also tested multifractal DFA. Analyses of SG data using multifractal DFA in this study were unable to associate the shape, width, or position of the multifractal spectrum with CGM device type or sensor location.…”

Accuracy of a Novel Noninvasive Transdermal Continuous Glucose Monitor in Critically Ill Patients

“…30 In other reports, Jacobs et al showed that their subcutaneous CGM was not sufficiently accurate outside of the euglycemic spectrum 31 and Brunner et al did not appreciate a difference in the control of glycemic variability in their retrospective study of 63 patients. 32 The clinical accuracy of different continuous monitors in various clinical settings is still being explored. However, it is clear that there is need for a more efficient way of measuring BG in the ICU.…”

Using Continuous Glucose Monitoring Data and Detrended Fluctuation Analysis to Determine Patient Condition

“…More recently, they have begun to be used in critical care patients and neonates to help monitor and monitor dysglycemia. [18][19][20][21][22][23][24] In an attempt to obtain a better insight into biomedical signals researchers have turned toward advanced time series analysis methods. In particular, detrended fluctuation analysis (DFA) has been a topic of many recent studies into glycemic dynamics.…”

“…In particular, detrended fluctuation analysis (DFA) has been a topic of many recent studies into glycemic dynamics. 19,[25][26][27] DFA investigates the "complexity" of a signal, how one point in time changes relative to its neighboring points. In the simplest of terms DFA characterizes the variability or "fuzziness" of a signal.…”

“…[28][29][30][31][32][33][34] However, DFA requires a large, densely measured time series, limiting the signals it is applied to. Thus, analyzing the glucose metabolic system with such signal processing tools as DFA is enabled by the emergence of high quality CGM devices that allow researchers to investigate if glucose complexity can be related to mortality 19,25 or other outcomes.…”